Scriber



Oct. 6, 1942. G. w. BRA-rcHER E-'rAL I scRIBER Filed may 23, 1941Patented Oct. 6, 1942 SCRIBER Gordon W. Bratcher and Jarl' W. Hanson,Duluth, Minn.

Application May 23, 1941, Serial No. 394,892

3 claims.

This invention relates to scribing tools, and has particular referenceto one especially adapted for use in the removal of emulsion from thesurface of lrns used in making contact impressions on zinc plates forphoto-lithographie or photo-offset printing, and one which may be usedfor scribing lines on the zinc plate itself.

The principal object of the invention is to provide a more practicaltool for this purpose and one which will make lines in the emulsion oron the plate having perfectly smooth edges with no ragged areas thereinthat might interfere with the reproduction of a perfect line.

Another object is to provide such a tool of fixed gage for the formingof lines of predetermined width.

Another object is to provide a tool for the forming of double or triplelines when desired.

Other objects and advantages of the invention will appear in thefollowing description thereof.

Referring now to the accompanying drawing, forming part of thisapplication, and wherein like reference characters indica-te like parts:

Figure 1 is a side elevation of one of our improved scribing tools, asused, with the exception that a suitable handle may be riveted orotherwise attached thereto.

Figure 2 is an edge view of Figure 1.

Figure 3 is a View of the head of a scriber in action and illustra-testhe curling away from the cutting edge of the tool of the ribbon of theemulsion from a film.

Figure 4 is an enlarged longitudinal central sectional view of a doubletool for the making of double lines.

Figure 5 is an enlarged elevation of the head end of the scriber,illustrating one concaved side thereof.

Figure 6 is simply a representation of the type of lines which may beaccomplished on the iilrn or plate by the scriber.

The instrument is formed of relatively thin, iiat tool steel and of theform shown in Figure 1 which is a full-size side elevation of theinstrument, the upper end of the handle portion tapering as indicated atI to the narrow neck immediately adjacent the head 2 of the instrument.The upper edge of the head is illustrated as being in the form of an arcof a circle though no particular shape thereof is essential. However,from the point indicated at 3 to the cutting edge of the tooth the edgeof the head is preferably straight, which provides convenience inplacing the tool at the proper angle on the film or plate so that thecutting edge leads properly.

The sides 5 of the tool are generally perfectly flat, but from a shortdistance downwardly from the free end of the head portion to the teeth 4the sides are slightly concaved, transversely, as clearly illustrated atE, to provide the positive marginal terminus of said teeth. Furthermore,the edges of the portions, indicated at l, leading from the cutting edgeof the teeth to the shank,

are also concaved, or hollow ground, for the purpose desired, beingformed with a circular or spherical grinding tool.

Consequently it is apparent that the teeth 4 are formed by an acuteangle, and the edge of one leg 1 of said angle being hollow ground,presents a sharp cutting edge at each side of each tooth 4, and whichwhen drawn along the emulsion on a lm insures the positive and cleancutting thereof to produce the perfect line desired therein.

Thus, with the exception of the slightly concaved portion on oppositesides of the head, the tool is flat so that two of the same may beplaced side by side for the purpose of providing a double scribing toolas shown in Figure 4 of the drawing, and wherein an intermediate spacerstrip, indicated at 8, is employed. This spacer strip may be of anydesired width to provide the proper spacing between the two tools, whendouble lines, such as indicated at 9, may be made.

The doube headed feature of the tool has further novelty in that eachcutting edge 4 thereof is of diierent width so that each tool isequipped to make either of two lines of diii'erent width. In mostbookkeeping forms there are light and heavy lines and thus by providingthe tool with different predetermined widths, at the cutting edges 4,one tool can produce either type of line desired. This feature is alsotrue in the case of the single tool illustrated in Figures 1 and 2.

There is suggested in dotted lines the approximate position of grindingunits for accomplishing the desired shape of the tool, and at I0 isillustrated a hole through the instrument for convenience in suspendingthe same when not in use.

Having thus described our invention, what we claim and desire to secureby Letters Patent, is:

1. A tool for scribing lines in the emulsion on the surface of lms usedin lithographie or offset printing, including a handle, a head havingsides and edges issuing from one end of said handle, said sides beingconcaved on an axis at right angles to said tool axis, and a scribingtooth at one edge of said head, the leading face 3. A tooth for a toolfor scribing lines in the emulsion on the surface of lms used inlithographic or offset printing, comprising a scribing edge formed bythe intersection of the edges of said tooth, the leading face of saidtooth when scribing, being concaved both transversely andlongitudinally.

GORDON W. BRATCHER. JARL W. HANSO-N.

